Laser recrystallization of ion-implanted Si by frequency-doubled Nd:YAG laser

Abstract
We have investigated the recrystallization of ion‐implanted amorphous Si using a frequency‐doubled, 10−8 s pulsed Nd:YAG laser. The samples used had been implanted with As ions in the energy range 50 to 140 keV, at dosages between 1014 and 2×1017 cm−2. The threshold energy density is approximately 0.5 J/cm2. Using depth profiles obtained from He‐ion backscattering, we have established that the resistivity displays the well known concentration dependence. Raman spectra of laser annealed samples have also been used to characterize the stages of anneal. In particular, the Fano shift of the phonon frequency gives an indirect measure of the carrier concentration. Preliminary TEM studies show an annealed sample 2×1015 As/cm2 to be almost free of dislocation at 0.7 J/cm2. It is possible to avoid surface damage by proper selection of energy densities.